This invention is related to so-called curtain valves wherein the valve member is a flexible element that can be displaced over a passageway inside of a valve to control the fluid flow through the valve. More particularly this invention is related to curtain valves wherein the valve element is supported and displaced by the motion of rollers.
In the art relating to curtain valves, the valve constructions follow several general configurations. In one of these configurations exemplified by Barneby, U.S. Pat. No. 3,828,816 issued Aug. 13, 1974, the flexible valve element is an impervious sheet mounted between reels at opposite ends of a grid so the sheet can slide across the grid as the reels are rotated. Another general configuration exemplified by Burdock, U.S. Pat. No. 3,410,311 issued Nov. 12, 1968, has flexible valve member secured at one edge of a port and extending thereform around a roller to a take-up reel which stores the unused portion of the flexible member. The roller moves across the part and pulls the valve member across the port to close the valve. In another configuration the curtain valve (shown in Fox, U.S. Pat. No. 3,905,576 issued Sept. 16, 1975) has a pair of endless bands supported on rollers and arranged in a side by side relation such that one portion of the bands resides in a face-to-face relation and outer portions of the bands face outward to block inlet and outlet parts of the valve.
The disadvantages of the above noted prior art curtain valves are as follows:
In the first configuration and in the second configuration the flexible member must be maintained in sufficient tension in order to prevent the flexible member from fluttering or vibrating excessively in the fluid flow. A valve of either of these configurations would be most likely restricted to relatively low fluid flow rates due to vibration of the flexible valve member. Also, in these two configurations considerable force may be required on the part of an operator or actuator for the valve in order to precisely position the valve member and restrain it from flow induced forces in the valve.
In the third configuration a large number of parts are required to accomplish the desired result and these must be precisely constructed and kept clean and free to move in order to prevent the valve member from jamming as the rollers move in the up and down motion to open and close the valve.
This invention utilizes a mechanism that is designated as a rolamite. This rolamite mechanism is described in a publication titled "Rolamite: a New Mechanical Design Concept", Research Report SC-RR-67-656A, pages 116, 119, Dec. 1967, D. F. Wilkes, 1322 Sandia Laboratory, Albuquerque, N.M. The rolamite mechanism is also shown as a vibration detector in the Harrah et al, U.S. Pat. No. 3,698,351 issued Oct. 17, 1972.